avgw.c File Reference

Weighted average. More...

#include "sqlstat.h"

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Classes
struct	avgw_storage
	Storage for weighted average. More...

Functions
my_bool	avgw_init (UDF_INIT *initid, UDF_ARGS *args, char *message)
	Called before first usage of function. More...
void	avgw_reset (UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error)
	Reset function and add first group member Calls clear and add. More...
void	avgw_clear (UDF_INIT *initid, char *is_null, char *error)
	Called at start of group. More...
void	avgw_add (UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error)
	Add a member of the group. More...
double	avgw (UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error)
	Retrieve weighted average. Called at end of group. More...
void	avgw_deinit (UDF_INIT *initid)
	Called after last access to function. More...

Detailed Description

Weighted average.

CREATE AGGREGATE FUNCTION avgw RETURNS REAL SONAME 'libsqlstat.so';
SELECT avgw(x, w) FROM mytab;
DROP FUNCTION avgw;

Definition in file avgw.c.

Function Documentation

double avgw	(	UDF_INIT *	initid,
		UDF_ARGS *	args,
		char *	is_null,
		char *	error
	)

Retrieve weighted average. Called at end of group.

Parameters

initid	function description
args	argument values
is_null	result is NULL
error	error message

Returns

weighted average

Definition at line 157 of file avgw.c.

void avgw_add	(	UDF_INIT *	initid,
		UDF_ARGS *	args,
		char *	is_null,
		char *	error
	)

Add a member of the group.

The sums are updated

Parameters

initid	function description
args	argument values
is_null
error	error message

Definition at line 125 of file avgw.c.

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void avgw_clear	(	UDF_INIT *	initid,
		char *	is_null,
		char *	error
	)

Called at start of group.

void avgw_clear(UDF_INIT *initid, char *is_null, char *error) The sums are cleared.

Parameters

initid	function description
is_null
error	error message

Definition at line 108 of file avgw.c.

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void avgw_deinit

(

UDF_INIT *

initid

)

Called after last access to function.

Deallocate memory for counter and sums.

Parameters

initid

Definition at line 177 of file avgw.c.

my_bool avgw_init	(	UDF_INIT *	initid,
		UDF_ARGS *	args,
		char *	message
	)

Called before first usage of function.

Check parameters.
Indicate type of return value.
Allocate memory for sums.

Parameters

initid	function description
args	parameters
message	error message

Returns

success = 0

Definition at line 55 of file avgw.c.

void avgw_reset	(	UDF_INIT *	initid,
		UDF_ARGS *	args,
		char *	is_null,
		char *	error
	)

Reset function and add first group member Calls clear and add.

Parameters

initid	function description
args	argument values
is_null
error	error message

Deprecated:

Reset is only called by MySQL 4.0 and below. It is implemented for backwards compatibility.

Definition at line 94 of file avgw.c.

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